In 1992, a small biotech company in Cambridge, England announced the creation
of "Astrid," the world's first "transgenic" pig. Soon scientists were talking
seriously about "organ farms" that would solve the world's chronic shortage of
hearts, livers and other spare parts for human transplantation. A new breed of
pigs, genetically-altered to be more human--and,so, less likely to be rejected
by the immune systems of human recipients--was riding into town to save the
day.

Now, five years after the first clinical human trials were first predicted to
have begun, the most hopeful members of the xeno community still see trials
several years away, and a number of scientists and scientific organizations are
expressing new cautions. At the same time, a new possible solution to the
organ shortage--creating organs from human stem cells, then cloning them--has
emerged as a potentially more promising long-term solution. All of this is
effecting the business of xeno: The science ultimately might prove workable,
but will the money for the research hold out through more years of
unprofitability and potential controversy?

The current wave of cautions about xeno is in no way the last word, and growing
organs from human stem cells is not without serious problems of its own: Stem
cell science is in its infancy, and the research quickly runs into two deeply
contentious ethical and political debates--abortion and cloning--which could
prevent it from progressing, at least in the United States. This brings
everyone interested in solving the world's organ shortage back to the original
riddle: Will the world's transgenic pigs ever fly? The answer is no joke to
the companies who have staked almost a billion dollars over the last decade on
making it happen.